In an automated information storage and retrieval library system, each piece of media (such as magnetic tape or an optical disk) on which data is recorded is generally housed within a rigid cartridge body for protection and ease of handling. Because the cartridge is handled by humans (loading and removing the cartridge into and from the library), a mechanical accessor (internally transporting the cartridge between a storage cell and a data drive) and a data drive (loading and interfacing with information on the media), information pertaining to the cartridge must be available to a human operator, the mechanical accessor and the data drive. Cartridge identifying information can include, for example, the cartridge's volume serial number. Media information can include, for example, the media length or size, media capacity, and whether the cartridge is a cleaner cartridge used for cleaning the data drives.
Conventionally, the human readable information and the machine readable information have been treated separately on the cartridge. Typically, the human readable information has been printed on a stick-on label in an appropriate language while the machine readable information has taken any of several forms. Identifying information (such as the volume serial number of the cartridge) can be encoded on a label in numbers readable by a vision system or can be printed in bar code format readable by a bar code scanner. However, both of these require optical and decoding systems with relatively sensitive optical and mechanical alignment and generally do not include the media information. Media information can be provided through the use of mechanical fingers in the data drive which activate or deactivate corresponding switches when they detect holes in predetermined locations on the cartridge housing. The presence or absence of a hole in a particular location is indicative of certain media information. Because each media information code combination is represented by a different hole pattern formed when the cartridge housing is manufactured, each requires a different manufacturing mold and a separate inventory for each cartridge housing configuration. Moreover, since the human readable information is applied as a label or the like to the housing after the housing has been manufactured and the media added to it, there is increased risk that the human and machine readable information may not be consistent.